Acid-soluble plug forming rapidly dehydrating loss control slurry

ABSTRACT

A rapidly dehydrating lost circulation material (LCM) composition that forms an acid-soluble plug is provided. The LCM composition may include a carrier fluid, an acid-soluble-particulate material, a viscosifier, and date tree rachis fibers. The carrier fluid may be water and the viscosifier may be a cellulosic microfiber. The LCM composition may alter a lost circulation zone by forming an acid-soluble plug in a fracture of the lost circulation zone. The acid-soluble plug may be removed via an acid solution, such as a hydrochloric acid solution. Methods of lost circulation control and manufacture of a rapidly dehydrating LCM are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.62/431,726 filed Dec. 8, 2016, and titled “ACID-SOLUBLE PLUG FORMINGRAPIDLY DEHYDRATING LOSS CONTROL SLURRY.” For purposes of United Statespatent practice, this application incorporates the contents of theProvisional application by reference in its entirety.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to controlling lost circulationin a wellbore during drilling with a drilling fluid. More specifically,embodiments of the disclosure relate to a lost circulation material(LCM).

Description of the Related Art

Lost circulation is one of the frequent challenges encountered duringdrilling operations. Lost circulation can be encountered during anystage of operations and occurs when some or all of the drilling fluid(which may include drilling mud) pumped into a well does not return tothe surface. While a de minimis amount of fluid loss is expected,excessive fluid loss is not desirable from a safety, economical, orenvironmental point of view. Lost circulation is associated withproblems with well control, borehole instability, pipe sticking,unsuccessful production tests, poor hydrocarbon production after wellcompletion, and formation damage due to plugging of pores and porethroats by mud particles. In extreme cases, lost circulation problemsmay force abandonment of a well.

Lost circulation can occur in various formations, such as naturallyfractured formations, cavernous formations, and high permeableformations. Lost circulation may also occur due to induced fractures inweak formations. Lost circulation due to induced fractures may occurwhen the mud weight needed for well control and to maintain wellborestability exceeds the fracture gradient of the formations. Depletedreservoir formations that have a low fracture gradient may besusceptible to induced loss circulation. Due to the narrow mud weightwindow for mud used in such formations, drilling of some depleted zonesmay be difficult without incurring induced loss circulation because themud weight used to support the formation can easily exceed the fractureresistance of the formation. Induced loss circulation may also occur dueto the inability of the drilling mud to remove low and high gravitysolids from the wellbore. The accumulation of solids in the mud mayincrease the fluid density beyond the upper limit of the mud weightwindow and create induced fractures in the formation.

SUMMARY

Different types of traditional and specially designed loss controlmaterials, slurries, and pills are used to control lost circulation.Loss control materials may generally be classified into severalcategories, such as surface plastering and shallow plugging materials,fracture sealing and deeper plugging materials (also referred to as“loss control slurries”), and interstitial bridging and pore pluggingmaterials. Such lost circulation materials (LCMs) are used to mitigatethe lost circulation by blocking the path of the drilling mud into theformation. The type of LCM used in a lost circulation situation dependson the extent of lost circulation and the type of formation.

Lost circulation may occur in either the non-reservoir and reservoirsections, or both, of a wellbore. Certain LCMs may be more suitable foruse in reservoir sections of a reservoir. For example, LCMs that areremovable via acid washes that degrade over time or that are oil solublemay be suitable for use in the reservoir sections of a wellbore.Consequently, a smaller number of LCMs are available to combat loss ofcirculation in the reservoir section of a wellbore.

A challenging situation arises in depleted reservoirs due to the ease ofcreation of induced loss circulation. Because the mud weight required tosupport the formation can easily exceeds the fracture gradient of theformation due to narrow mud weight window, the drilling of some depletedzones may be very difficult without incurring induced loss ofcirculation. As some LCMs may cause permanent damage to depleted oil andgas reservoirs, a non-damaging (for example, acid-soluble, degradable,or oil soluble) LCM may be suitable for combating loss of circulation indepleted oil and gas reservoirs.

Induced loss circulation may also occur in non-depleted reservoirs dueto the inability of the drilling mud to remove low and high gravitysolids from the wellbore. The accumulation of the solids in the mud mayincrease the fluid density beyond the upper safe limit of the mud weightwindow and result in the creation of induced fractures in the reservoirformation, leading to moderate to severe lost circulation. Some LCMs maycause severe damage to the reservoir and result in a drastic loss ofwell productivity. In such instances, a non-damaging (for example,acid-soluble, degradable, or hydrocarbon soluble) LCM may be moresuitable to avoid a severe impact on the productivity of a well andrecovery from a reservoir.

Many commercial LCMs, such as loss control pills and slurries are notsuitable for controlling loss of circulation encountered in thereservoir section of a borehole due to their detrimental effect on wellproductivity and the recovery from the reservoir. Moreover, someconventional LCMs and lost circulation pills typically fail when used inmoderate to severe fluid loss conditions. Moreover, conventional losscontrol pills and slurries also lack the ability to seal and blockmoderate to severe loss zones. Additionally, lost circulation can causeenvironmental problems if drilling fluids or LCMs interact with theenvironment surrounding the reservoir. Thus, there is a need for LCMs toovercome the lost circulation related drilling challenges in the payzone without hampering the productivity of a well and ultimate recoveryof a field, especially in moderate to severe loss zones.

Embodiments of the disclosure generally relate to an acid-solubleplug-forming rapidly dehydrating LCM composition (also referred to as arapidly dehydrating fluid (RDF)) to control lost circulation in a lostcirculation zone in a wellbore. More specifically, embodiments of thedisclosure relate to a rapidly dehydrating LCM composition that includesa carrier fluid, an acid-soluble particulate material (for example,calcium carbonate), a viscous material (also referred to as a“viscosifier”), and an organic fibrous material (for example, fibersformed from the rachis of date trees).

In one embodiment, a lost circulation material (LCM) composition isprovided. The LCM composition includes a carrier fluid, an acid-solubleparticulate material, a viscosifier, and a fibrous material thatincludes date tree rachis fibers. In some embodiments, the carrierfluid, the particulate material, the viscosifier, and the fibrousmaterial form a homogenous mixture. In some embodiments, the carrierfluid comprises water. In some embodiments, the viscosifier includes acellulosic microfiber. In some embodiments, the acid-soluble particulatematerial includes calcium carbonate. In some embodiments, the calciumcarbonate is at least 4% weight of the total weight (w/w %) of the LCMcomposition. In some embodiments, the date tree rachis fibers compriseat least 4% weight of the total weight (w/w %) of the LCM composition.In some embodiments, the LCM composition has a dehydration time of lessthan 3 minutes at 100 pounds-per-square inch differential (psid)pressure.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore. The method includes introducing analtered drilling fluid into the wellbore such that the altered drillingfluid contacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone. The altered drilling fluidincludes a drilling fluid and a lost circulation material (LCM)composition. The LCM composition includes a carrier fluid, anacid-soluble particulate material, a viscosifier, and a fibrous materialthat includes date tree rachis fibers. In some embodiments, the methodincludes introducing an acid solution into the wellbore such the acidsolution contacts a plug formed by the LCM composition in the lostcirculation zone. In some embodiments, the acid solution includeshydrochloric acid. In some embodiments, the method includes adding theLCM composition to the drilling fluid to create the altered drillingfluid. In some embodiments, the carrier fluid, the particulate material,the viscosifier, and the fibrous material form a homogenous mixture. Insome embodiments, the carrier fluid comprises water. In someembodiments, the viscosifier includes a cellulosic microfiber. In someembodiments, the acid-soluble particulate material includes calciumcarbonate. In some embodiments, the calcium carbonate is at least 4%weight of the total weight (w/w %) of the LCM composition. In someembodiments, the date tree rachis fibers comprise at least 4% weight ofthe total weight (w/w %) of the LCM composition. In some embodiments,the LCM composition has a dehydration time of less than 3 minutes at 100pounds-per-square inch differential (psid) pressure.

In some embodiments, an altered drilling fluid is provided that includesa drilling fluid and a lost circulation material (LCM). The LCMcomposition includes a carrier fluid, an acid-soluble particulatematerial, a viscosifier, and a fibrous material that includes date treerachis fibers. In some embodiments, the carrier fluid comprises water.In some embodiments, the viscosifier includes a cellulosic microfiber.In some embodiments, the acid-soluble particulate material includescalcium carbonate. In some embodiments, the calcium carbonate is atleast 4% weight of the total weight (w/w %) of the LCM composition. Insome embodiments, the date tree rachis fibers comprise at least 4%weight of the total weight (w/w %) of the LCM composition.

In another embodiment, a method of forming a lost circulation material(LCM) is provided. The method includes adding a carrier fluid to form amixture and adding an acid-soluble particulate material to the mixture.The method further includes adding viscosifier to the mixture and addinga fibrous material to the mixture, the fibrous material comprising datetree rachis fibers.

In some embodiments, the LCM composition comprises a homogenous mixture.In some embodiments, the carrier fluid comprises water. In someembodiments, the viscosifier includes a cellulosic microfiber. In someembodiments, the fibrous material consists of date tree rachis fibers.In some embodiments, the particulate material consists of calciumcarbonate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of fibers produced from the date tree waste inaccordance with an embodiment of the disclosure;

FIG. 2 is a photograph of an acid-soluble plug in a test cell and formedafter a dehydration test of an example LCM composition in accordancewith an embodiment of the disclosure;

FIGS. 3 and 4 are photographs of acid-soluble plugs and formed by thedehydration test of example LCM compositions in accordance with anembodiment of the disclosure;

FIG. 5 is a photograph of the initial stage of interaction between aplug formed by an example LCM composition and an acid solution inaccordance with an embodiment of the disclosure;

FIG. 6 is a photograph of the final stage of interaction between a plugformed by the an example LCM composition and an acid solution inaccordance with an embodiment of the disclosure; and

FIG. 7 is a block diagram of a process for the use of a rapidlydehydrating LCM composition in accordance with an embodiment of thedisclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully with referenceto the accompanying drawings, which illustrate embodiments of thedisclosure. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

As a wellbore is drilled, a drilling fluid is continuously pumped intothe wellbore to clear and clean the wellbore and the filings. Thedrilling fluid is pumped from a mud pit into the wellbore and returnsagain to the surface. A lost circulation zone is encountered when theflow rate of the drilling fluid that returns to the surface is less thanthe flow rate of the drilling fluid pumped into the wellbore, and it isthis reduction or absence of returning drilling fluid that is referredto as lost circulation.

The present disclosure includes compositions for use as a lostcirculation material (LCM) to mitigate or prevent such lost circulationin a well and prevent or reduce the loss of drilling mud while drilling.The compositions described in this disclosure may create an acid-solubleplug in a fracture of a formation to reduce or prevent the loss ofdrilling mud into the surrounding formation. In some embodiments, theLCM compositions described in this disclosure can squeeze out all of thefluid phase in a range of about 1.5 minutes to about 3 minutes at about100 psid (pounds per square inch differential) or more of overbalancepressure. Further, the compositions described in this disclosure areeco-friendly, non-toxic, and environmentally safe such that the use ofsuch compositions for lost circulation control will have little to nodetrimental effects on the subsurface environment and surroundingaquifers.

Additionally, the compositions described in this disclosure use rawmaterials that may be available locally and may encourage economic andjob growth of local industries, such as the date farming industry. Thecompositions described in the disclosure also provide a viable recyclingpath for date tree waste (that is, portions of the date tree discardedafter production of dates). Further, the production of compositions fromlocally available raw materials may reduce or eliminate the importationof conventional LCMs.

The present disclosure includes rapidly dehydrating LCM compositions tocontrol lost circulation in a lost circulation zone in a wellbore. Insome embodiments, a rapidly dehydrating LCM composition includes acarrier fluid, an acid-soluble particulate material, a viscous material(also referred to as a “viscosifier”), and date tree rachis fibers as afibrous material. In some embodiments, the rapidly dehydrating LCMcomposition includes water as the carrier fluid, calcium carbonate asthe acid-soluble particulate material, a cellulosic microfiberviscosifier, and fibers produced from date trees (also referred to as“date palms”) as the fibrous material. FIG. 1 is a photograph 100 offibers produced from the date tree waste in accordance with anembodiment of the disclosure. As used in the disclosure, the term datetree waste refers to the waste produced from processing date trees (alsoreferred to as “date palms”) in the production of date fruits (alsoreferred to as “dates”). The fibers may include, by way of example,fibers produced from date tree rachis (also referred to as “date treerachis fibers”). In some embodiments, the LCM composition may form or bereferred to as a rapidly dehydrating fluid (RDF).

Examples

The following examples are included to demonstrate embodiments of thedisclosure. It should be appreciated by those of skill in the art thatthe techniques and compositions disclosed in the example which followsrepresents techniques and compositions discovered to function well inthe practice of the disclosure, and thus can be considered to constitutemodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or a similar result without departing from the spirit and scope ofthe disclosure

The following non-limiting examples of LCM compositions were preparedand evaluated to determine the rapidity of dehydration, the plug formingcapabilities, and the acid solubility potential of the formed plug.Table 1 shows the formulations of the example LCM compositions used inthe tests, with compositions of the components provided in milliliters(ml) or grams (g), and also expressed as weight of the total weight (w/w%) of the LCM composition

TABLE 1 LCM formulations for dehydration testing Amount ComponentDescription Formulation 1 Formulation 2 Water (ml) Carrier Fluid 350 350Particulate Calcium 40 (9.5 w/w %) 20 (4.8 w/w %) Material (g) Carbonate(CaCO₃) Viscosifier (g) Betafib ® 15 (4.0 w/w %) 15 (3.6 w/w %) FibrousMaterial Date Tree Rachis 15 (4.0 w/w %) 30 (7.2 w/w %) (g) Fibers

Formulation 1 used medium grade calcium carbonate particles having a D50particle size distribution value in the range of about 135 microns toabout 165 microns. Formulation 2 used fine grade calcium carbonateparticles having a D50 particle size distribution value of about 10microns to about 14 microns. As shown in Table 1, each formulationincluded a cellulosic microfiber viscosifier, Betafib®, manufactured byCosun Biobased Products of Roosendaal, Netherlands. Each formulationalso included a fibrous material of rachis fibers obtained from the datetree phoenix dactylifera.

The two formulations were tested using the following dehydration testprocedure using an American Petroleum Society (API) filter press havinga filtration cell to contain the LCM composition undergoing testing:

1. Prepare formulation by mixing each component in a commercial drillingfluid mixer to form a homogenous mixture;

2. Fill filtration cell of API filter press with a 350 cubic centimeter(cc) pill of the formulation;

3. Mount filtration cell to API filter press, affix the upper lid, andconnect an air pressure line of nitrogen gas at about 100 psid pressure;and

4. Measure the dehydration time of the pill (that is, the time for thefluid (about 350 cc) to be removed) at room temperature and 100 psidpressure and collect discarded fluid (that is, expelled carrier fluid)in a fluid collection pot at the bottom outlet of the API test cell.

The results of the dehydration test procedure for the tested LCMcompositions for both formulations are shown in Table 2, with thedehydration time measured in minutes (min) and the thickness of the plugformed by the dehydrated pill measured in millimeters (mm):

TABLE 2 Dehydration Testing results Formulation 1 Formulation 2Dehydration time 3 1.55 (min) Plug Thickness (mm) 43.259 44.45

FIG. 2 is a photograph 200 of an acid-soluble plug formed after thedehydration test according to the procedure described supra. As shown inTable 2, for a 350 cc pill in the API filtration cell under 100 psidifferential (psid) pressure, each formulation exhibited dehydrationtime of less than 3 minutes (that is, a solid plug was formed in 3minutes or less dehydration time under 100 psid pressure). The firstformulation exhibited a dehydration time of about 3 minutes, and thesecond formulation with a lower concentration of acid-solubleparticulate and a higher amount of fibrous material exhibited adehydration time of less than 2 minutes. The variation in dehydrationtime between each formulation may be dependent on the concentration ofacid-soluble particulate material (for example, calcium carbonate),fibrous material (for example, date tree rachis fibers), or both. Eachformulation formed acid-soluble plugs having a nearly equal plugthickness, thus indicating similar performance in a potential loss zone.Thus, each of the tested formulations may thus be suitable as a rapidlydehydrating LCM composition to block fractures of different dimensionsand reduce or prevent loss of drilling mud in, for example, moderate tosevere loss zones of hydrocarbon reservoirs.

The acid solubility of the plug was evaluated by observing the plug'sphysical condition and mechanical stability before and after adding a 15w/w % hydrochloric (HCl) acid solution to the RDF. For example, FIG. 3is a photograph 300 of the acid-soluble plug formed by the dehydrationtest of the first formulation of the LCM composition. In anotherexample, FIG. 4 is a photograph 400 of the acid-soluble plug formed bythe dehydration test of the second formulation of the LCM composition

The acid solubility of the plugs formed by the two formulations wastested using the following test procedure:

1. Transfer the plug formed during the dehydration test to a glassbeaker;

2. Pour 15 w/w % hydrochloric acid (HCl) solution in an amountsufficient to completely submerge the plug; and

3. Wait from about 5 minutes to about 8 minutes to dissolve theacid-soluble particulate material of the plug.

During the dissolution of the acid-soluble particulate material, anincreasing volume of foam was generated, followed by a stabilization ofand minor changes in foam generation, and then by a progressivelydecreasing rate of foam generation. For example, FIG. 5 is a photograph500 of the initial stage of interaction between a plug formed by thetest LCM composition and the acid solution, and FIG. 6 is a photograph600 of the final stage of interaction between a plug formed by the testLCM composition and the acid solution.

As the test procedure was conducted on unconfined plugs, the plugsdispersed completely due to the interaction of the acid and theparticular material, resulting in complete dispersion of the fibernetwork formed by the fibrous materials. The dispersed fibers remainedintact due to poor acid solubility. Both formulations demonstrated theformation of acid-soluble plugs that were easily dissolved by an acid(for example, hydrochloric acid). Thus, each of the tested formulationsmay be usable as a rapidly dehydrating LCM composition that provides forsubsequent removal of a plug formed by the composition via an acid wash,such as before completion of the well.

Rapidly Dehydrating LCM Compositions

In some embodiments, a rapidly dehydrating LCM (also referred to as aloss control slurry) may include a carrier fluid, a fibrous material, anacid-soluble particulate material, and a viscosifier. The carrier fluidmay include fresh water, seawater, brines or formation fluid. Thefibrous material may include a fibrous material derived from date treewaste, such as date tree rachis fibers. The acid-soluble particulatematerial may include calcium carbonate. The viscosifier may include asuitable commercial viscosifier that can provide for rapid dehydrationof the slurry under 100 to 500 psid overbalance pressure. In someembodiments, the fibrous material may include date tree rachis fibers.Example compositions are shown supra in Table 1.

In some embodiments, a rapidly dehydrating LCM composition may include acarrier fluid, an acid-soluble particulate material, a viscosifier, anda date tree rachis fibers. In some embodiments the carrier fluid mayinclude water. For example, the carrier fluid may include freshwater(water having relatively low (that is, less than 5000 ppm)concentrations of total dissolved solids), seawater (for example, waterhaving a salinity in the range of about 33,000 to about 37,000parts-per-million (ppm)), artificial brines, natural brines, brackishwater, or formation water.

In some embodiments, the acid-soluble particulate material of the LCMcomposition may include calcium carbonate. In some embodiments, theparticulate material of the LCM composition may include medium gradecalcium carbonate particles having a D50 particle size distributionvalue in the range of about 135 microns to about 165 microns. In someembodiments, the particulate material of the LCM composition may includefine grade calcium carbonate particles having a D50 particle sizedistribution value of about 10 microns to about 14 microns. In someembodiments, the particulate material of the LCM composition may includeboth medium grade and fine grade calcium carbonate particles, or calciumcarbonate particles having other sizes. In other embodiments, otheracid-soluble particular materials may be used.

In some embodiments, the viscosifier may include a cellulosic microfiberderived from raw vegetable materials. In some embodiments, theviscosifier may have be a non-toxic viscosifier having cellulose in therange of about 5 w/w % to about 25 w/w % and water, and a pH in therange of about 3 to about 6. In some embodiments, the viscosifier mayinclude Betafib® manufactured by Cosun Biobased Products of Roosendaal,Netherlands.

In some embodiments, a rapidly dehydrating LCM composition may includewater as a carrier fluid, calcium carbonate as an acid-solubleparticulate material, a cellulosic microfiber as a viscosifier, and datetree rachis fibers as a fibrous material. In some embodiments, thecalcium carbonate may be in the range of about 4 w/w % to about 10 w/w%. In some embodiments, the date tree rachis fibers may in the range ofabout 3 w/w % to about 8 w/w %. In some embodiments, when subjected to asqueezing or overbalance pressure, the rapidly dehydrating LCMcomposition may eliminate all of a fluid phase in 3 minutes or less atabout 100 psid overbalance pressure or less than about 2 minutes at 100psid overbalance pressure.

In some embodiments, when subjected to a squeezing or overbalancepressure, the rapidly dehydrating LCM composition can form anacid-soluble plug in a fracture to prevent or reduce the loss ofdrilling mud into the surrounding formation. In some embodiments, arapidly dehydrating LCM composition may have a greater concentration offibrous material (for example, date tree rachis fibers) to form a plughaving a relatively greater thickness, as compared to rapidlydehydrating LCM composition having lesser concentrations of the fibrousmaterial. The acid-soluble plug is dissolvable by an acid, such ashydrochloric acid or other mineral acids. For example, the acid-solubleplug may be dissolved by a 15% hydrochloric acid solution. In otherembodiments, other acid solutions may be used to dissolve theacid-soluble plug formed by the rapidly dehydrating LCM composition.

In some embodiments the fibrous material of the LCM composition mayinclude date tree rachis fibers (that is, a material composed of suchfibers). The date tree rachis may be obtained from date tree waste, suchas produced as a waste by-product from date processing, and the datetree waste may be obtained from date processing plants to providesustainable source of particulate material. Moreover, local sources ofdate tree waste may reduce the cost of imported LCM products,components, or both. In some embodiments, the date tree waste may beobtained from the species phoenix dactylifera. It should be appreciatedthat, in some embodiments, the date tree waste may be obtained fromgenetically modified date trees (that is, genetically modified organisms(GMOs)). In some embodiments, the date tree rachis may be prepared bycleaning the rachis, such as by blowing air over the rachis to removedust, rubbish, and other material, and then chopping, crushing, andgrinding the rachis using an industrial grinder to produce date treerachis fibers. In some embodiments, the processed fibers may be siftedvia a sieve to obtain a desired size of the fibrous material for us inthe LCM composition described in the disclosure.

In some embodiments, the date tree rachis fibers may include untreateddate tree rachis fibers, thus preserving the environmentally-friendlyand biodegradable properties of the manufacturing process, the fibers,and the resulting LCM composition. As used in the disclosure, the term“untreated” or “without treating” refers to not treated with alkali oracid, not bleached, not chemically altered, not oxidized, and withoutany extraction or reaction process other than possibly drying of water.The term “untreated” or “without treatments” does not encompass grindingor heating to remove moisture but does encompass chemical or otherprocesses that may change the characteristics or properties of thefibers. In such embodiments, the date tree fibers may be manufacturedwithout treating before, during, or after crushing, grinding, drying, orany other processing.

In some embodiments, a rapidly dehydrating LCM composition may be formedby adding a carrier fluid to a mixture, adding an acid-solubleparticulate material (for example, calcium carbonate) to the mixture,adding a viscosifier to the mixture, and adding a fibrous material (forexample, rachis fibers of a date tree) to the mixture. In someembodiments, the rapidly dehydrating LCM composition may be formed byfirst adding the carrier fluid, followed by adding the acid-solubleparticulate material (for example, calcium carbonate), followed byadding the viscosifier, and followed by adding a fibrous material (forexample, rachis fibers of a date tree). The LCM composition may beformed by mixing the carrier fluid, particulate material, viscosifier,and fibrous material in a high-speed mixer (for example, a commercialdrilling fluid mixture) and forming a homogenous mixture, such as ahomogenous fluid pill. In some embodiments, the LCM composition may bemixed for a time period (for example, in a range of about 4 minutes toabout 5 minutes) after the addition of each component. In someembodiments, the LCM composition may be mixed for another time period(for example, in a range of about 10 minutes to about 15 minutes) afterall components have been added to form a homogenous LCM mixture. In someembodiments the rapidly dehydrating LCM composition may be producedwithout any additives or treatments, thus preserving theenvironmentally-friendly and biodegradable properties of both themanufacturing process and the rapidly dehydrating LCM composition. Inother embodiments, the rapidly dehydrating LCM composition may be mixedor otherwise combined with additives or otherwise treated. In someembodiments, additives may be mixed or otherwise combined with the LCMto change the rheology or pH of the LCM. In some embodiments, suchadditives may include softening agents, surface active agents(surfactants), viscosity agents, thinning agents, dispersants, coatings(for example, pellet coatings), pH modifiers, insecticides, biocides, orany suitable combination thereof.

FIG. 7 depicts a process 700 for preparing and using a rapidlydehydrating LCM composition in accordance with an embodiment of thedisclosure. Initially, the rapidly dehydrating LCM composition may beformed from a carrier fluid, an acid-soluble particulate material, aviscosifier, and date tree rachis fibers (block 702). For example, insome embodiments, the rapidly dehydrating LCM composition may be formedby first adding the carrier fluid, followed by adding the acid-solubleparticulate material (for example, calcium carbonate), followed byadding the viscosifier, and followed by adding a fibrous material (forexample, rachis fibers of a date tree), and mixing in a high-speed mixer(for example, a commercial drilling fluid mixture) and forming ahomogenous mixture. In some embodiments, the LCM composition may bemixed for a time period (for example, in a range of about 4 minutes toabout 5 minutes) after the addition of each component and mixed foranother time period (for example, in a range of about 10 minutes toabout 15 minutes) after all components have been added to form an LCMpill (that is, a fluid pill formed of the LCM composition).

The LCM pill (also referred to an “RDF”) may be added to a drillingfluid, such as a drilling mud (block 704). For example, in someembodiments, the LCM pill may be added to (for example, blended with) anoil-based drilling mud or a water-based drilling mud. In someembodiments, an altered drilling fluid may be formed having the LCMpill. In some embodiments, the LCM pill may be added at the mud pit of amud system. After addition of the LCM pill, the drilling fluid havingthe LCM pill (that is, an altered drilling fluid) may be circulated at apump rate effective to position the LCM pill into contact with a lostcirculation zone in a wellbore (block 706). Next, a pressure may beapplied to form one or more acid-soluble plugs from the LCM pill, suchthat the rapidly dehydrating LCM composition of the pill alters the lostcirculation zone by forming one or more acid-soluble plugs in the porousand permeable paths, cracks, and fractures in a formation in the lostcirculation zone. As described supra, for example, in some embodimentsthe acid-soluble plugs may form in less than 3 minutes at a 100 psid.

Next, the acid-soluble plugs formed by the LCM composition may beremoved, such as by circulating an acid solution at a pump rateeffective to position the acid solution into contact with the plugs inthe lost circulation zone (block 710). For example, in some embodimentsa 15 w/w % HCl solution may be circulated to contact the plugs in thelost circulation zone to dissolve and remove the plugs. In otherembodiments, other suitable acid solutions (for example, differentconcentrations of HCl or solutions having other mineral acids such asnitric acid or sulfuric acid) may be used to dissolve and remove theplugs.

After removal of the plugs, further operations on the well (for example,cementing operations) may be performed. As noted in the disclosure, theeco-friendly, non-toxic, and environmentally friendly properties of therapidly dehydrating LCM composition may minimize or prevent anyenvironmental impact, any effect on ecosystems, habitats, population,crops, and plants surrounding the drilling site where the rapidlydehydrating LCM composition is used.

Ranges may be expressed in the disclosure as from about one particularvalue, to about another particular value, or both. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value, to the other particular value, or both, along withall combinations within said range.

Further modifications and alternative embodiments of various aspects ofthe disclosure will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the embodiments described inthe disclosure. It is to be understood that the forms shown anddescribed in the disclosure are to be taken as examples of embodiments.Elements and materials may be substituted for those illustrated anddescribed in the disclosure, parts and processes may be reversed oromitted, and certain features may be utilized independently, all aswould be apparent to one skilled in the art after having the benefit ofthis description. Changes may be made in the elements described in thedisclosure without departing from the spirit and scope of the disclosureas described in the following claims. Headings used described in thedisclosure are for organizational purposes only and are not meant to beused to limit the scope of the description.

What is claimed is:
 1. A lost circulation material (LCM) composition,the composition comprising: a carrier fluid; an acid-soluble particulatematerial; a viscosifier; and a fibrous material comprising date treerachis fibers.
 2. The LCM composition of claim 1, wherein the carrierfluid, the particulate material, the viscosifier, and the fibrousmaterial form a homogenous mixture.
 3. The LCM composition of claim 1,wherein the carrier fluid comprises water.
 4. The LCM composition ofclaim 1, wherein the viscosifier comprises a cellulosic microfiber. 5.The LCM composition of claim 1, wherein the fibrous material consists ofdate tree rachis fibers.
 6. The LCM composition of claim 1, wherein theacid-soluble particulate material comprises calcium carbonate.
 7. TheLCM composition of claim 6, wherein the calcium carbonate comprises atleast 4% weight of the total weight (w/w %) of the LCM composition. 8.The LCM composition of claim 1, wherein the date tree rachis fiberscomprise at least 4% weight of the total weight (w/w %) of the LCMcomposition.
 9. The LCM composition of claim 1, wherein the LCMcomposition has a dehydration time of less than 3 minutes at 100pounds-per-square inch differential (psid) pressure.
 10. A method tocontrol lost circulation in a lost circulation zone in a wellbore,comprising: introducing an altered drilling fluid into the wellbore suchthat the altered drilling fluid contacts the lost circulation zone andreduces a rate of lost circulation into the lost circulation zone,wherein the altered drilling fluid comprises a drilling fluid and a lostcirculation material (LCM) composition, wherein the LCM compositioncomprises: a carrier fluid; an acid-soluble particulate material; aviscosifier; and a fibrous material comprising date tree rachis fibers.11. The method of claim 10, comprising introducing an acid solution intothe wellbore such the acid solution contacts a plug formed by the LCMcomposition in the lost circulation zone.
 12. The method of claim 11,wherein the acid solution comprises a hydrochloric acid solution. 13.The method of claim 10, comprising adding the LCM composition to thedrilling fluid to create the altered drilling fluid.
 14. The method ofclaim 10, wherein the carrier fluid, the acid-soluble particulatematerial, the viscosifier, and the fibrous material form a homogenousmixture.
 15. The method of claim 10, wherein the carrier fluid compriseswater.
 16. The method of claim 10, wherein the viscosifier comprises acellulosic microfiber.
 17. The method of claim 10, wherein the fibrousmaterial consists of date tree rachis fibers.
 18. The method of claim10, wherein the particulate material comprises calcium carbonate. 19.The method of claim 18, wherein the calcium carbonate comprises at least4% weight of the total weight (w/w %) of the LCM composition.
 20. Themethod of claim 10, wherein the date tree rachis fibers comprise atleast 4% weight of the total weight (w/w %) of the LCM composition. 21.The method of claim 10, wherein the LCM composition has a dehydrationtime of less than 3 minutes at 100 pounds-per-square inch differential(psid) pressure.
 22. An altered drilling fluid, comprising: a drillingfluid; and a lost circulation material (LCM) composition, wherein theLCM composition comprises: a carrier fluid; an acid-soluble particulatematerial; a viscosifier; and a fibrous material comprising date treerachis fibers.
 23. The altered drilling fluid of claim 22, wherein thecarrier fluid comprises water.
 24. The altered drilling fluid of claim22, wherein the viscosifier comprises a cellulosic microfiber.
 25. Thealtered drilling fluid of claim 22, wherein the fibrous materialconsists of date tree rachis fibers.
 26. The altered drilling fluid ofclaim 22, wherein the particulate material comprises calcium carbonate.27. The altered drilling fluid of claim 26, wherein the calciumcarbonate comprises at least 4% weight of the total weight (w/w %) ofthe LCM composition.
 28. The altered drilling fluid of claim 22, whereinthe date tree rachis fibers comprise at least 4% weight of the totalweight (w/w %) of the LCM composition.
 29. A method of forming a lostcirculation material (LCM) composition, comprising: adding a carrierfluid to form a mixture; adding an acid-soluble particulate material tothe mixture; adding viscosifier to the mixture; and adding a fibrousmaterial to the mixture, the fibrous material comprising date treerachis fibers.
 30. The method of claim 29, wherein the LCM compositioncomprises a homogenous mixture.
 31. The method of claim 29, wherein thecarrier fluid comprises water.
 32. The method of claim 29, wherein theviscosifier comprises a cellulosic microfiber.
 33. The method of claim29, wherein the fibrous material consists of date tree rachis fibers.34. The method of claim 29, wherein the particulate material consists ofcalcium carbonate.